Induction-motor.



K. KUHLMANN & H. MULLER.

INDUCTION MOTOR.

APPLIOATION FILED 11.53.27, 1906.

Patented Mar. 5, 1912.

MTC/pagg' HEINRICH MULLER- m p @MQW/...H

UNITED STATES PATENT oEEIoE.

KAEL KUI'ILMANN, OE BERLIN-PANKOW, AND rIEINEICH MLLER, or BERLIN, GEE-MANY, AssIeNons To GENERAL ELECTRIC COMPANY, A CORPORATION OE NEW YORK.

lINDUCTION-MOTOR.

Specification of Letters Patent.

Application led March 27, 1906. Serial No. 308,269.,

To all whom Zt'may concern:

` Be it known that we, KARL KUHLMANN, a

subject of the Emperor of Germany, residing at Berlin-Pankow, Germany,and HEIN- RICH MLLER, a subject of the Emperor of Germany, residing atBerlin, Germany, have invented certain new and useful Improvements inInduction-Motors, of which the following is a specification.

Our invention relates to induction motors, and more especially tosingle-phase motors; and its object is to provide an improved form ofstarting device.

In order to prevent a heavy flow of current at starting, it is desirableto have ahigh resistance in the secondary circuit of an induction motor,which should be cut out when the motor is up to speed. For this purposeautomatic centrifugally-actuated devices have been employed heretoforeeither to short-Circuit a resistance in series with the secondarywinding or to close the circuit of an auxiliary secondary winding. Inorder to make single-phase induction`motors 'selfstarting, it isnecessary to arrange them with special connections at starting, eitherwith a special starting winding or with by reference to the accompanyingdrawings;

ning and vhaving phase-splitting devices, or both. The Ystartingconnections are broken and running connections established when themotor 1s up to speed. This has been accomplished heretofore bothmanually and automatically.

Our invention, in one aspect, consists in thecombination with analternating current motor having different 'connections of the primarymember for starting and for runtwo secondary windings, one a startingwinding and the other ay running winding, automatic means serving tochange the primary connections and also to short-circuit the secondaryrunning winding. V

Our invention also 'com rises a number of other features whichwillst beunderstood in Which- Figure 1 shows diagrammatically the ciri cuitconnections of a single-phase Induction motor arran ed in accordancewith our invention; an Figs. 2 and 3 show the construction o theautomatic ,starting device.

Inthe drawings, A represents the main rimary winding of the motor,adapted to ge connected through the main switch S to i and insulatedfrom a bearing o a source of alternating-current indicated by theconductors a. B represents the auxiliary startingv winding connected inparallel with the main windin and having in series with it the phase-sifting device b.

y C represents stationary collectorl rings connected in series with theauxiliary vwinding B. 1

c represents a Contact carried by the rotor and arranged at starting tobridge the collector rings G, so as to close the circuit of the startingwinding B.

The rotor or seconda member is shown provided with two win ings,-One asquirrel-cage starting winding D of high resistance; the other anopen-circuited coil running winding E of low resistance.

F represents a switch carried by the rotor and adapted to engage thecontacts f f connected to the low-resistance winding E, so as toshort-circuit this windingwhen the motor is up to speed.

The mechanical construction of the automatic device controlling both theContact c and the switch F is shown in Figs. 2 and 3. The contact c" iscarriedby a pivoted lever H, w 'ch is normally held by' a spring h inthe p sition shown in Fig. 2, so as to press the contact c intoengagement with the collector rings C, which may be supported upon `themotor, as indicated in dotted lines 1n Fig. .3. The switch member Fconsists of a sleeve loosely mountedon the shaft and provided withprojecting contact members adapted, when moved to the position shown indotted lines, to engage the stationary 'contacts f, which are connectedto points on the low-resistance winding, as shown in Fig. l. The memberF is engaged b`\a pin on the centrifugally-actuated mem er G. Atstarting this member is held by a spring g in the position shown in fulllines, thereby holding the switch member F outiof engagement withthe'contacts f. When the ,motor reaches a predetermined speed, themember 'G is thrown Outward by centrifugal force, asindifcated by thearrow into the position :Patented Mar. 5, 19.12.

shown in dotted lines, thereby shifting f switch member F into thedotted-line Aposition so as to short-circuit the low-resistance therebyraising contact c from collector rings C and opening the circuit of thestarting winding B. ln this manner a single device serves both to makethe necessary changes in the primary circuit from starting to runningconnections, and at the same time to decrease the e'ective resistance inthe secondary when ythe motor is up to speed. Since the centrifugaldevicerdoes not engage the lever H until it begins to move outward, thecontact c is held by its spring firmly on the collector rings until itis lifted quickly at the proper moment.

We do not desire to limit ourselves to the particular construction andarrangement of parts here shown, but aim in the appended claims to coverall modifications wh1ch are within the scope of oui1 invention. i

What we claim as new and desire to secure by Letters Patent oit' theUnited States,

i. ln combination with an alternating current motor having di'erentconnections of rent' motor having different connections of 'the primarymember for starting and for V'running and having twosecondary windings,one -a squirrel-cage starting winding of high resistance and the other arunning I Winding of low resistance, automatic means serving to changethe primary connections and also to short-circuit the secondary runningWinding.

3. ln a slngle phase motor, a primary member having a main windingand astart-- ing winding, a secondary member having a starting winding and arunning winding, and automatic means serving to cut the primarystart-ing winding out of circuit and also to short-circuit thesecondary7 running winding.

4.-. ln a single phase motor, a primary member having a main winding anda 'starting Winding, a secondary member having a squirrel-cage startingwinding.A of high re- `sistance and a running winding of lowresista-nce, and automatic means serving to cut the primarystartingWinding out of circuit and also to short-circuit the secondary runningwinding. i

5. ln combination with an alternatingi current motor havlng dierentconnectionsl of the primary member for starting and for Loiaeei runningand having two secondary wind-' ings, one sliort-circuited and of highresistance and the other open-circuited and oi2 low resistance,automatic means arranged both to change the primary connections and toclosethe circuit of the low-resistance Secondary winding when the motoris up t0 speed.

. 6. in combination with an alternating current motor having differentconnections of the primary member for starting and for running andhaving two secondary windings, one short-circuited and of highresistance and the other open-circuited and of 10W resistance,centrifugally-actuated means arranged both to change the primaryconnections and to close tlic circuit of the lowresistance secondarywinding when the motor is up to speed.

7. In an induction motor, a main primary winding, a starting winding, ahigh-resistance short-circui/ted secondary winding, a low resistanceopen circuited secondary winding, and a centrifugally-actuated devicearranged to open the circuit oitl the start` ing Winding and to closethe circuit of the. low-resistance secondarywinding when the motor is upto speed. i l

8. In yan induction motor, a stator and a rotor, a starting winding,stationary collector rings in circuit with said winding, a contactcarried by the rotor adapted to bridge said rings, other contactscarried by the rotor 'adapted to vary the effective resistance of vrotorladapted `to bridge said rings, and a centrifugal device carried by therotor and controlling said contact but separate therefrom.

l0. lin an induction motor, a starting winding, stationary collectorrings in circuit with said winding, a contact movably carried by therotor and adapted to bridge saidI rings, means for holding said contactin engagement with said rings at starting, and

a centrifugal device arranged to be out of engagement with said contactat starting,

but when moved by centrifugal force to engage and shift said-contact.

ln witness whereof, We have hereunto set our hands this 12th day ofMarch, 1906.

KARL KUHLMANN.

y y HELNRLCH MLLER.

- llitnesses: i. JULIUs RUMLAND, KARL Roemenen.

